1. Field of the Invention
This invention relates to a process for the production of supports suitable for catalysts to be used in various fields of chemical industry.
2. Prior Art
As concerns solid catalysts particularly for use in the hydrogenation of hydrocarbon residual oils, there have been made reports on the relationship between the specific surface area, the amount of active metals and the catalytic activity and between the pore size and the service life. Numerous methods have been proposed to this end to prolong the catalyst life by controlling or regulating its pore size. One such method involves increasing the size of the primary particles in an alumina gel as disclosed for instance in Japanese Patent Publication No. 56-35893. However, with this method it is difficult to provide a catalyst having a pore radius in a range 100 .ANG.-1,000 .ANG. which is required for effective hydrogenation of residual oils. A similar method is disclosed in Japanese Patent Laid-Open Publication No. 55-27830 whereby the size of gelled alumina particles can be controlled at will; however, the catalyst support is too much reduced in strength and specific gravity to warrant commercial application.
According to J. Catalysis, 1, 547 (1962), an alumina hydrogel is combined with a water-soluble polymer such as polyethylene glycol or the like to thereby form a catalyst predominantly of pore radii exceeding 1,000 .ANG. and hence with reduced packing density.
In Japanese Patent Laid-Open Publication No. 52-104498 it is proposed to allow an alumina hydrogel to absorb polyethylene glycol, followed by extrusion molding and washing with alcohol. Japanese Patent Laid-Open Publication No. 57-201532 discloses introducing carbon black in particulate alumina. Japanese Patent Publication No. 59-23859 is directed to the use of a refractory inorganic oxide in combination with a peptizer and a surfactant. These methods, though capable of giving a pore radius range of 100 .ANG.-500 .ANG., fail to selectively control the pore size within that range, if possible, only to limited extent.
The foregoing prior art methods would lead, given greater pore sizes, to catalysts of insufficient strength, reduced specific surface area and low packing density, the latter two parameters being literally undesirable for catalytic reactions involving hydrogenated desulfurization, denitrification, demetalation and thermal decomposition.
It has been found that crude oils imported nowadays are rather heavy, widely variable in grade and irregular in polymeric materials containing vanadium or nickel. This has created an urgent need for improved catalysts which are capable of treating such oil fractions.